The Origin of Chrysanthemum Segctiun Plenum. 187 
We thus see that the limit has been reached. Any 
further improvement of the race will only increase the 
number of doubles and consequently of sterile individ- 
uals. Seed-parents therefore must always be chosen 
amongst the plants with the same degree of "doubling" 
as in this year (1900). In this respect my new race be- 
haved, immediately after its origin, exactly like the old- 
established Chrysanthemum inodorum plenissimum. 1 
It still remains to give some account of the general 
conditions of fertilization of the seed-parents in the vari- 
ous years. No doubt the experiment would have been 
purer and more demonstrative if the corn marigold were 
capable of self-fertilization. But this either does not 
occur at all, or only to a totally inadequate extent. Each 
year I have therefore left a group of a few selected plants 
to flower together after the eradication of the rest; and 
have been obliged to content myself with collecting the 
seed of each in a separate package. Future experiments 
will have to determine what the effect of this crossing 
o 
may have been on the progress of the race. Meanwhile 
it may be of interest to place on record the number of 
plants which have flowered together each year, showing 
the stringency of selection to which they were subjected. 
In the summer of 1895 the original parent of the 
whole race, which was raised from seeds obtained by ex- 
change (1895, No. 1), could not be isolated until late 
and then incompletely, but as the plants flowering at the 
same time also belonged to the 21 -rayed race the curve 
of the offspring was very "pure" in this respect (p. 176). 
In the next year the number of seed-bearers was reduced, 
about the middle of August, to three very vigorous incli- 
1 The Matricaria ftore _ toto albo plenissinw, described by MUN- 
TING in 1871, the best specimens of which also set no seed, was prob- 
ably the same variety (Waare Oeffeningc der Planten, p. 527). 
